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  • Richard

Cranfield 'Reinvented Toilet'

In the midst of Regulating CWIS case studies, I have been having a look at the final version of Cranfield's 'Nano-membrane' 'Reinvented Toilet', courtesy of Bill & Melinda Gates Foundation funding.

I had been part of this research at the beginning, contributing to the 2012 Inception meeting and subsequent early meetings, necessarily dropping out as the CW+ rural water study in India took up all my time at Cranfield.

What is fascinating looking back, at least to me, is how some of the earliest design concepts were eventually absorbed into the finished product.

In the minutes of the Inception meeting I included this diagram, below, of how I saw it being necessary to give the appearance of a standard household 'white good' which could be easily purchased and installed in, for example, a multi-storey block of flats which had not been developed with adequate sanitation.

Also pleased to note that in the second or third weekly meeting we had included the concept of a screw pump, I was thinking of a progressive cavity pump as used in the food industry but I see now the final design includes a more conventional archimedes screw pump.

I continue to be intrigued by the idea of the surround to the pump could be some form of membrane, to reduce the water content whilst the 'solids' (faecal matter, no longer very solid) are lifted in preparation for further treatment and removal.

The finished design:

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